(09-07-2013 10:03 AM)TwoCultSurvivor Wrote: Ok, but if we keep the simplicity of it, then you see the basis of my question.

You said eight light years, right? So how do I not conclude that the light from the supernova traveling to planet B is not moving at a relative velocity of 2c (relative to the light traveling to planet C)?

In other words, if two objects are traveling away from each other, each at the speed of light, isn't their relative speed 2c?

You have to apply the Lorentz transformation in this case: both are moving with velocity c, that is, u = c and v=c. Therefore,

This you speak of is Time Dilation , and you are indeed correct, this simply disproves the Earth is less than 14 billion years young . The moon infact we see at a later date. During the moon landing, you could not simply view them with a telescope at that exact time.

As for the size...There are many theories. For one, the universe is slightly curved, but that turns into "What is outside of the curve, since there is some reason for the curvature ? " . No one knows yet. I believe its expanding so far and is so fast, we as a species may never know.

" My friends. You bow to no one. " - Aragorn

"A man is accepted into a church for what he believes and he is turned out for what he knows. " — Samuel Clemens

There are two kinds of motion. Real motion - e.g. photons travelling from the Sun to Earth travelling at 300,000,000 metres per second take about 8 to 9 minutes. Then there is 'Apparent velocity' - a characteristic of the Expansion of the Universe. Since the space in between galaxies is expanding everywhere, the compound effect when viewing the most remote (proto) galaxies is that they appear to be travelling very close to the speed of light. Whether real or apparent, objects travelling away from us at or above the speed of light cannot be observed since the photons can never reach us.

The Observable Universe (from Earth) is about 13.7 Billion light years (BLY), that's a radius. One can hypothesize that the proto galaxies at 13.7 BLY also emitted light in the opposite direction to Earth and those photons will now be 27.4 BLY from Earth. This gives a value of 27.4 BLY for 'R' in the volume of a sphere (also a guess) 4/3(π r**3) ('four-thirds pi r cubed'). The technical/scientific term for something this large is 'king enormous.

Observers on Earth will probably never see anything beyond the Background Microwave Radiation; there is almost certainly 300,000 Light years of opaque residue from the Big Bang.

Quote:Accordingly, we might wonder: How large is the part of the universe we’re potentially able to observe directly? At first glance, the answer might seem like a simple calculation. The speed of light is approximately 186,282 miles per second, or about 5.9 trillion miles per year. The time that has elapsed since the Big Bang is 13.75 billion years. Multiple the two figures and—voilà—we find that over the entire history of the universe, light could have travelled 13.75 billion light-years, or 81 billion trillion miles. But, in fact, that answer would be wrong.